Stroke is one of the leading causes of death and disability worldwide and places a heavy burden on the economy in our society. Current treatment strategies for stroke primarily focus on reducing the size of ischemic damage and on rescuing dying cells early after occurrence. Treatments, such as the use of thrombolytic agents, are often limited by a narrow therapeutic time window. However, the regeneration of the brain after damage is still active days, or even weeks after stroke occurs, which might provide a second window for treatment. Our preliminary data suggests that systemic in vivo delivery of a peptide that blocks a specific receptor mediated inhibitory action of sulphated proteoglycans in the glial scar in stroke animals 24 hours after stroke or 7 days after stroke both improve their functional recovery. We hypothesize that the CSPG signaling pathway is involved in the regulation of neuroregeneration and axonal sprouting after stroke and that modulating the CSPG signaling pathway will lead to better functional outcome in stroke recovery. We will test this hypothesis in both young and aged mice in the proximal transient middle cerebral artery occlusion (MCAo) animal model. Towards this goal, we have developed a proposal that consists of three specific aims. In specific aim 1 and 2, we will investigate the role of the CSPGs signaling pathway in functional recovery in young or aged stroke animals. In specific aim 3, we will examine the mechanisms of neurorepair in stroke animals by combination of genetic and pharmacological modulation with inducible cell type specific RPTP? knockout or ISP peptide treatment. Two main mechanisms of neurorepair including neurogenesis and axonal sprouting in stroke will be analyzed in genetically and pharmacologically modulated stroke animals. Together, the comprehensive analysis of molecular, cellular and behavioral measurements in stroke animals will generate data that will provide insights on the precise role of CSPG signaling in the process of injury-induced neurorepair. The data gained will be directly applicable to developing novel therapeutic interventions in treating cerebral ischemia through the manipulation of the cellular microenvironment in the CNS. We anticipate that the resources and results generated from our study will open new avenues in neuroregeneration research and lead to the identification of molecular therapeutic targets.